[Leetcode]147. Insertion Sort List

Sort a linked list using insertion sort.

链表的插入排序

思路，递归到链表尾，然后循环插入；

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */     
class Solution {
    public ListNode insertionSortList(ListNode head) {
        if (head==null||head.next==null)
            return head;
        head.next = insertionSortList(head.next);
        ListNode p = head;
        while (p.next!=null){
            if (p.val>p.next.val){
                int tmp = p.val;
                p.val = p.next.val;
                p.next.val = tmp;
            }
            p = p.next;
        }
        return head;
    }
}